This week, astronomers announced they’ve found eight new planets that could be “just right” for supporting human life. These planets, found in the “Goldilocks” zone of their respective stars, are of so much interest because their orbits put them at a distance where liquid water, the basis of life on Earth, could naturally occur.
While eight planets might not seem like much, the discovery doubles the number of small planets considered to be potentially habitable. Among these eight, the team identified two that stand out as being more similar to Earth than any other exoplanet they’ve studied to date.
What sets the two planets – Kepler-438b and Kepler-442b – apart is the amount of sunlight they receive. Too much light and the water evaporates into steam. Too little and the water freezes.
Kepler-438b receives almost one and a half the amount of light we get on Earth, and as a result, researchers estimate it has a 70 percent chance of being in the habitable zone. Venus, by comparison, is the hottest planet in our home solar system with only twice the light that Earth gets.
Most exciting is Kepler-442b, which gets two-thirds as much light as Earth; it has a 97 percent chance of being in the Goldilocks zone.
“We don’t know for sure whether any of the planets in our sample are truly habitable,” says study co-author David Kipping in a press release for the Harvard-Smithsonian Center for Astrophysics (CfA). “All we can say is that they’re promising candidates.”
The team looked at planetary candidates first identified by NASA’s Kepler mission. Normally astronomers would confirm the bodies were planets by measuring their mass, but because the candidates were so small the team validated them by using a computer program called BLENDER – the same method responsible for some of Kepler’s most noteworthy discoveries, including the two planets found to be the same size as Earth that also orbit a Sun-like star.
BLENDER was developed by CfA’s Guillermo Torres and Francois Fressin, and runs on the Pleiades supercomputer at NASA Ames, which is currently ranked as the eleventh-fastest system on November’s TOP500 list. Pleiades sports a LINPACK rating of 3.38 petaflops and a peak performance of 4.49 petaflops following the addition of 15 SGI ICE X racks this past October. The ultimate goal of the SGI-NASA partnership is to push Pleiades’ peak capacity to 10 petaflops.
As for the BLENDER analysis, after its completion the team spent another year gathering follow-up data from high-resolution spectroscopy, adaptive optics imaging, and speckle interferometry to better understand the systems that BLENDER identified, but because the newly discovered planets are so far away, additional observations would be a challenge. Kepler-438b is found 470 light-years from Earth while Kepler-442b is 1,100 light-years away.
“Each result from the planet-hunting Kepler mission’s treasure trove of data takes us another step closer to answering the question of whether we are alone in the Universe,” NASA associate administrator John Grunsfeld reported in a press release. “The Kepler team and its science community continue to produce impressive results with the data from this venerable explorer.”